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问题 My task seemed to be really easy: Use the TagGroup and extract the tree structure and the data of an unknown structure into the result log. So I want to get the name and the value and all the names and values of the children to be displayed in the results. How do I do this? I have the following (example) Tag structure: The documentation writes about the TagGroup and also contains one example using TagGroupGetTagType() . The returned value can then be used to find the structure. I wrote and

问题 Swift 5.1 . Consider the following. let x: Any? = nil let y: Any = x print("x \(x)") // x nil print("type(of: x) \(type(of: x))") // type(of: x) Optional<Any> print("x == nil \(x == nil)") // x == nil true print("y \(y)") // y nil print("type(of: y) \(type(of: y))") // type(of: y) Optional<Any> print("y == nil \(y == nil)") // y == nil false We have two variables, set equal to the same thing - nil. They print the same, their type prints the same - but one == nil and the other does not. Why?

问题 I am building a classical Nim game using only the array , and I found there is a bug after testing. If I successfully create a player, I'll assign a new object to the array. However, when removing the player in the array, I filter the array with non-null objects because I have other functions such as editplayer , displayplayer to iterate the entire array without NullPointerException . And there is a chance that this happens: addplayer → removeplayer → addplayer . It means I'll always get

问题 Since C++11, the Standard allows the macro NULL to either be a integer literal with value zero, or a prvalue of type std::nullptr_t . Any Standard Library vendor deciding to change their definition of NULL from an integer to nullptr would very likely cause breakage for clients relying on pre-C++11 code. Does any major implementation (e.g. GCC, Clang, MSVC) actually define NULL as nullptr ? Or, despite the possibility, does nobody do this? 回答1: libstdc++ relies on including stddef.h, which

问题 Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers. Want to improve this question? Update the question so it's on-topic for Stack Overflow. Closed 6 years ago . My assumption followed by question based on the assumption: Javascript has null and undefined . You can set a variable to be null , implying it has no value, or you can set it to undefined , implying that it isn't known whether it has a value or not - it's just not set at all. PHP has

问题 I am trying to contol a buttons state depending on a relevant text box. The names are the same other than the prefixes. The text boxes and buttons are located in a table on the page. <asp:Table ID="Table1" runat="server" CssClass="table"> <asp:TableRow> <asp:TableCell Width="15%"> <asp:Label ID="lblRequestHeader" runat="server" Text="Requested" CssClass="bold text-center" Width="90%"></asp:Label> </asp:TableCell> <asp:TableCell Width="15%"> <asp:Label ID="lblApprovalHeader" runat="server"

问题 I am trying to contol a buttons state depending on a relevant text box. The names are the same other than the prefixes. The text boxes and buttons are located in a table on the page. <asp:Table ID="Table1" runat="server" CssClass="table"> <asp:TableRow> <asp:TableCell Width="15%"> <asp:Label ID="lblRequestHeader" runat="server" Text="Requested" CssClass="bold text-center" Width="90%"></asp:Label> </asp:TableCell> <asp:TableCell Width="15%"> <asp:Label ID="lblApprovalHeader" runat="server"

问题 I am trying to contol a buttons state depending on a relevant text box. The names are the same other than the prefixes. The text boxes and buttons are located in a table on the page. <asp:Table ID="Table1" runat="server" CssClass="table"> <asp:TableRow> <asp:TableCell Width="15%"> <asp:Label ID="lblRequestHeader" runat="server" Text="Requested" CssClass="bold text-center" Width="90%"></asp:Label> </asp:TableCell> <asp:TableCell Width="15%"> <asp:Label ID="lblApprovalHeader" runat="server"

问题 I want to make method that will check if the class instance is null or not. Simply I know that i can use == null , but I want to know that is there any other way that can be implemented to check if instance is null or not ? I have nearly 70-80 class instance. & all that class extend same Class BaseEntity . at time of declaration I have declare each instance like : Entity1 instance1 = null; like so I have defined all 70 class instances . when they will be used I am initializing them using new.

问题 I want to make method that will check if the class instance is null or not. Simply I know that i can use == null , but I want to know that is there any other way that can be implemented to check if instance is null or not ? I have nearly 70-80 class instance. & all that class extend same Class BaseEntity . at time of declaration I have declare each instance like : Entity1 instance1 = null; like so I have defined all 70 class instances . when they will be used I am initializing them using new.